Grip end bottom additional-weighting weight, and grip end bottom additional-weighting structure

ABSTRACT

A weight that is composed of a composite of a soft material and a loading member which is a high specific gravity substance and that is mounted on a grip end bottom of a ball-hitting implement, allowing the loading member to be divided into an internal weighting element and an external weighting element; and a grip end bottom weighting structure that uses this weight, in which the center of gravity is shifted closer to the portion grasped by hand, and the node of vibration on the grip is shifted to the grip fulcrum. When mounted, the loading member is disposed on either side of the grip end member, with soft material region interposed therebetween. The weight is at least flexible enough to be easily mounted and to be adjusted in balance, and it will not come off during play. This makes the ball-hitting implement head-light (grip-heavy) just prior to impact, which improves the player&#39;s swing or stroke, and also increases the moment of inertia around the center of gravity at the instant of impact and further suppresses or absorbs (attenuates) the vibration caused by impact.

TECHNICAL FIELD

[0001] This invention relates to a grip end bottom weight and a grip endbottom weighting structure for a ball-hitting implement. The terms“weight” and “weighting body,” “weighting weight” and “balance adjustingweighting body,” and “center of impact (non-impact position)” and “nodeof vibration” are each used interchangeably.

BACKGROUND ART

[0002] In the field of ball-hitting implements, and particularly tennisrackets, it has long been the practice to lighten the racket body tomake the racket easier to swing, and to adjust the balance (distributethe weight) to shift the center of gravity of the racket.

[0003] There have also been proposals aimed at reducing discomfort suchas numbness or excessive load on the body by suppressing or absorbing(attenuating) the impact vibration at the instant the ball is hit.

[0004] For instance, Japanese Patent 2,853,926 and Japanese PatentApplication Laid-Open No. H4-263876 disclose the provision of this sortof means to a grip end.

[0005] In these prior art, it is proposed that a loading member(weighting body) be mounted as a vibrator via an impactvibration-absorbing member. The effect of this proposal is said to bethat it eliminates the increase in impact that occurs when aconventional weight is directly mounted to a grip end.

[0006] With the above prior art, however, the impact vibration-absorbingmember and the loading member are either housed within the grip orattached on the outside; and there is no mention of the importance ofbalancing (weight distribution), especially as regards the weightpertaining to the weighting structure of the present invention (anincrease in the moment of inertia around the center of gravity), nor isthere any mention that the feel of hitting the ball is improved when thenon-impact position (node of vibration) of the two-node flexuralvibration on the grip produced when the racket hits the ball is shiftedto the portion grasped by the hands (grip fulcrum).

[0007] Meanwhile, an overview of the main balancing means (includingstabilizers) used to absorb impact vibration reveals that some areprovided to the racket head (frame) or the middle part (throat), ratherthan to the grip end, but there is no mention whatsoever of thestructure of the present invention, so a proposal such as this isoutside the body of prior art.

[0008] In light of this, the inventor has already proposed a “BalancingWeighting Body for Ball-Hitting Implement” (Japanese Patent ApplicationNo. 2000-65171). In this application, the balancing means required tosolve the above problem, and more specifically, a balancing weightprotruding from the grip end bottom of a ball-hitting implement, isprovided. The center of gravity position is shifted toward the portiongrasped by the hands, and the moment of inertia around the center ofgravity is increased, which raises head speed by facilitating snapmovement centered around the wrist, and also absorbs impact vibration,thereby improving the characteristics of the ball-hitting implement.

[0009] The characteristic feature proposed here is to provide abalancing weight protruding from the bottom of the grip end cap or endrubber of the ball-hitting implement; and while the general object andeffect were the same as in the present invention, there is room forimprovement in the weight and the attendant weighting structure,including the distribution of weight for moving the center of impact(node of vibration) on the grip.

[0010] The general trend in tennis rackets in recent years has been tomake them lightweight and top-heavy. This means that the node ofvibration on the grip is farther away from the grip end when the ball ishit. While this does improve rebound, it also increases impact(vibration). The node of vibration is usually 90 to 180 mm away from thegrip end, although this varies with differences in weight distribution.

[0011] The present invention is conceived in light of this situation;and it provides a grip end bottom weight and a grip end bottom weightingstructure which raise the level of play, and afford simple mounting onthe grip end bottom, which makes a racket easier to handle, which inturn increases head speed, and improves the damping effect (especiallymoving the node of vibration on the grip) in order to prevent injury andmake it more comfortable to hit the ball.

[0012] As to applications of the present invention, a tennis racket istypical; however, the present invention is not limited to this and canbe applied to soft tennis rackets, squash rackets, badminton rackets, orother such rackets, or to baseball or softball bats, golf clubs, groundgolf clubs, gate ball clubs, hockey sticks, and other such ball-hittingimplements.

DISCLOSURE OF INVENTION

[0013] In the present invention, a weight is provided so as to protrudefrom the grip end bottom of a tennis racket or other ball-hittingimplement, which increases the moment of inertia around the center ofgravity when a ball is hit, and also suppresses, absorbs, or attenuatesimpact vibration. At the same time, hitting the ball becomes morecomfortable because the center of impact (node of vibration) on the gripis shifted to the portion grasped by the hands (grip fulcrum).

[0014] More specifically, the above structure provides head-light(grip-heavy) with the ball-hitting implement just prior to impact, whichmakes the implement easier to handle, and the moment of inertia aroundthe center of gravity is increased at the instant of impact, so theplayer's swing or stroke is not overcome by the ball.

[0015] Furthermore, weighting balance can be adjusted by varying theweight distribution of the loading member or the mounting position ofthe weight.

[0016] The first invention is a grip end bottom weight (hereinafterreferred to as “weight”), characterized in that a soft material, capableof absorbing impact vibrations and compositely integrated with a loadingmember composed of a high specific gravity substance, has axiallysymmetric wall thickness in cross section and can be mounted byelastically deforming a body component into a mounting hole formed inthe grip end bottom, and at least the half of the body componentprotrudes from the grip end bottom after mounting. The weight here isdesigned such that the center of impact (node of vibration) on the gripis shifted to the portion grasped by the hands (grip fulcrum).

[0017] The second invention is a grip end bottom weighting structure(hereinafter referred to as “weighting structure”), characterized inthat the above-described weight is removably mounted on the grip end ofa ball-hitting implement, the moment of inertia around the center ofgravity is increased at the moment a ball is hit, and impact vibrationis suppressed, absorbed, or attenuated.

[0018] Here, the grip end bottom weighting structure includes a grip endmember including an end cap or end rubber and having a mounting holeformed in the planar center, a loading member composed of a highspecific gravity substance, and a soft material compositely integratedwith the loading member, and the soft material has axially symmetricwall thickness in cross section and can be mounted by elasticdeformation of a body component, at least the half of the body componentis fixed to protrude from the grip end bottom of the ball-hittingimplement, and a soft material region is interposed in the grip endmember so as to isolate the loading member.

[0019] In the present invention constituted as described above, thecomposite integration results in the loading member being incorporatedinto, embedded in, surrounded by, joined to, compounded with, ordispersedly compounded with in a matrix of the soft material. As will bediscussed below, the typical shape of the soft material is anapproximate barrel shape, and a circumferential groove or flange isprovided around the large-diameter middle of the soft material. A bodycomponent is elastically deformed and non-rotatably restrained (fitted)in a mounting hole, and the soft material is balance-mounted, with onehalf of the body housed inside the grip via the side walls of themounting hole, and the other half of the body protruding from the gripend bottom. This prevents the weight from coming loose during play.

[0020] Also, the mounting hole is formed by boring out the bottomsurface of a grip end member including an end cap or end rubber.

[0021] Also, the soft material is mounted by being removably fitted,pressed, squeezed, or threaded into the mounting hole by stored elasticenergy.

[0022] Further, the loading member is disposed at the two ends of thesoft material, with its weight divided into an internal weightingelement and an external weighting element when mounted.

[0023] In view of the above, mounting the weight structured as above ona ball-hitting implement increases the moment of inertia around thecenter of gravity when the ball is hit and thus increases rebound andabsorbs (attenuates) impact vibration. At the same time, the weight isdistributed so that the center of impact (node of vibration) on the gripis shifted to the portion grasped by the hands (grip fulcrum), sohitting the ball is more comfortable.

[0024] As a result, the implement is head-light (grip-heavy) when nothitting a ball (until just prior to impact); and it is easier to snapthe implement around the wrist, head speed is higher, the implement iseasier to swing, and it is easier to put spin on the ball.

[0025] The weighting structure in which the above-described weight isused can be applied to a grip end of tennis rackets, soft tennisrackets, squash rackets, badminton rackets, or other such rackets, or tobaseball or softball bats, golf clubs, hockey sticks, and other suchball-hitting implements.

BRIEF DESCRIPTION OF DRAWINGS

[0026]FIG. 1 is a diagram illustrating a standard tennis racket, whichrepresents a ball-hitting implement;

[0027]FIG. 2(a) is a partially cut-away front view of the weight, andFIG. 2(b) is a left side view thereof;

[0028]FIG. 3 is a cross sectional view of the weighting structure;

[0029]FIG. 4 is a cross sectional view of a modified example ofEmbodiment 1;

[0030]FIG. 5 is a cross sectional view of another modified example ofEmbodiment 1;

[0031]FIG. 6 is a cross sectional view of yet another modified exampleof Embodiment 1;

[0032]FIG. 7 is a cross sectional view of an example of application to agolf club;

[0033]FIG. 8 is a cross sectional view of another weight and theweighting structure thereof; and

[0034]FIG. 9 is a cross sectional view of yet another weight and theweighting structure thereof.

BEST MODE FOR CARRYING OUT THE INVENTION

[0035] The present invention will now be described in further detailwith reference to the accompanying drawings.

[0036] Embodiment 1

[0037] A standard tennis racket is shown in FIG. 1. In FIG. 1, AE is theoverall length of the racket, B is the impact point (range), C (beforeweight is mounted) and C′ (after weight is mounted) are the racketbalance point (center of gravity) when a ball is not being hit, and D(before weight is mounted) and D′ (after weight is mounted) are thecenter of impact on the grip (node of vibration). The impact force withthe ball acts on B when the ball is hit.

[0038] As shown above, when the weight W is mounted at the grip endbottom, the center of gravity of the racket when no ball is being hitshifts from C to C′. Therefore, the center of gravity shifts toward theportion grasped by the hand, which makes snap movement easier andincreases head speed.

[0039] Also, the center of impact on the grip (node of vibration) shiftsfrom D to D′. When the player employs a standard grip, the portiongrasped by the hand (grip fulcrum) is located about 7 cm away from thegrip end, and when D′ comes to this position, the player is gripping thenode of vibration, which minimizes impact vibration and makes hittingthe ball more comfortable.

[0040] The basic vibration of a racket when a ball is hit is two-nodeflexural vibration, with the nodes of vibration being on the grip andthe string plane (the so-called sweet spot approximated by B); but ifthe hand grasps the node on the grip, and the ball is hit at the node onthe string plane (center impact), then the vibration (energy)transmitted to the hand will be minimized and loss of rebound of theracket will also be avoided.

[0041] The weight design of the weight based upon experimental findingsis verified as follows:

[0042] When a 50 g weight is mounted on the grip end bottom of a 300 gracket, the node of vibration shifts from a position 12 cm away from thegrip end (before the weight is mounted) to a position 7 cm away. Ingeneral, if the weight of the weight is increased or decreased by 10 g,the node of vibration on the grip will shift 1 cm.

[0043] As seen from the above, when a weight is thus mounted to the gripend bottom, the node of vibration on the grip shifts in the grip enddirection. Incidentally, if the distal end of the frame is weighted withan eye toward increasing rebound, the node of vibration will shift inthe opposite direction, so the object and effect of this is differentfrom those of the present invention.

[0044] Therefore, in order to shift the node of vibration on the grip(90 to 180 mm from the grip end) to the portion usually grasped by thehand (60 to 80 mm from the grip end in the case of a single hand grip)on a lightweight, top-heavy racket, a weight of 10 to 120 g is mountedto the grip end bottom. In the case of a double hand grip, the weightingdesign should be made so as to shift the node of vibration to a position70 to 140 mm, and preferably 80 to 120 mm, from the grip end.

[0045] As shown in FIG. 2, the weight W is comprised of a soft material2 (such as natural rubber, or a silicone or other synthetic rubber),capable of absorbing impact vibrations and compositely integrated with aloading member 1 (such as lead) composed of a high specific gravitysubstance, including this loading member 1, being incorporated into,embedded in, surrounded by, joined to, compounded with, or dispersedlycompounded with in the soft material 2. This soft material 2 has axiallysymmetric wall thickness in cross section and is molded in theapproximate shape of a barrel, and a circumferential groove 21 isprovided around the large-diameter middle.

[0046] As shown in FIG. 3, a body component is elastically deformed intoa mounting hole 41 formed in the grip end bottom of a tennis racket, sothat the body component is fitted to the peripheral edge of the mountinghole 41. One half of the body is housed inside the grip via the sidewalls of the mounting hole 41, while the other half of the bodyprotrudes from the grip end bottom and is thus balance-mounted.

[0047] Accordingly, when mounted, the loading members 1 are isolated bythe soft material 2 region interposed in the grip end member 4 thatincludes an end cap.

[0048] The weighting range should be individually selected for each userso that play will not be hindered; and for practical purposes theweighting range is 10 to 120 g, and preferably 10 to 80 g. In commercialproduct form, the weight W is provided to the market in differentclasses or grades depending on how much each weight weighs.

[0049] The weight W here is such that the loading members 1 are disposedat two ends of the soft material 2, with its weight divided into aninternal weighting element 11 and an external weighting element 12 whenmounted.

[0050] In terms of balancing, the internal weighting element 11 and theexternal weighting element 12 may be either equal or unequal loads. Ifthe load is unequal, the product can be designed so that the weightingbalance between the internal weighting element 11 and the externalweighting element 12 is changed by switching the mounting direction.

[0051] A protective cap for preventing the weight from falling out maybe provided. FIG. 4 illustrates a modified example thereof.

[0052] The shape of the loading member 1 and how it is integrated(compounded) can vary; and the loading member 1 can be incorporatedinto, embedded in, surrounded by, joined to, compounded with, ordispersedly compounded with (composite) in a matrix of the soft material2. A modified example is shown in FIG. 5.

[0053] The internal weighting element 11 does not necessarily have to bea loading member. It can instead be substituted with the weight of thesoft material 2 itself if the space this soft material takes up isenlarged. A modified example of this is shown in FIG. 6.

[0054] The mounting hole 41 is made by boring out the bottom surface ofan end cap (or a grip end member 4 including the same), and anengagement means that allows fitting, pressing, squeezing, or threadingin conjunction with the weight W (soft material 2) is formed at theperipheral edge or end face of this mounting hole 41. The configurationof this means should be tailored to the intended application to variousball-hitting implements. For the sake of reference, FIG. 7 shows anapplication example of mounting to the end rubber bottom of a golf club.

[0055] Embodiment 2

[0056] As shown in FIG. 8, the soft material 2 is formed in theapproximate shape of a barrel, just as in Embodiment 1; but acircumferential flange 22 is provided around the large-diameter middleinstead of the circumferential groove 21. Therefore, a mating groove isformed in the end face of the mounting hole 41, and the circumferentialflange is fitted therein. The only difference here is that themale/female orientations of the fitting members (2 and 4) are reversed.

[0057] Embodiment 3

[0058] As seen from FIG. 9, shown therein is an example of anotherweighting structure, in which the ball-hitting implement is providedwith two end caps or is provided with a single cap that is formed thickso that the mounting hole is provided in two levels or steps. As aresult, the mounting position can be changed. Such a balancing means canbe variously modified as long as the essence of the weighting structureof the present invention is kept.

[0059] The weights in the above-described embodiments can be marketed asa set with a grip end member in which a mounting hole is formed, andprovided as a part of a constituent member of the grip end.

[0060] The essence of the present invention should understood from thevarious embodiments given above, but the protected scope of the presentinvention is not limited by these embodiments; and various modificationsare possible as long as the requirements below are met.

[0061] In the constitution of the weight, it is important that thisweight be a composite of a loading member and a soft material and thatthe loading member be divisible into an internal weighting element andan external weighting element.

[0062] Also, in the constitution of the weighting structure in whichthis weight is used, it is important that the mounted loading member beisolated by a soft material region interposed in the grip end memberthat includes an end cap, and that this weighting structure at least beeasy to mount and afford versatility in balancing, that is, allow theweight distribution to be easily changed by remounting.

[0063] Naturally, all of this must not compromise the operation andeffect of the present invention, namely, that there be an increase inthe moment of inertia around the center of gravity when a ball is hit,and that impact vibration be suppressed or absorbed (attenuated).

Industrial Applicability

[0064] As discussed above, according to the present invention, a loadingmember composed of an internal weighting element and an externalweighting element is disposed at the grip end bottom of a ball-hittingimplement, and the center of gravity of the implement is shifted towardthe portion grasped by hand, which makes the implement head-light(grip-heavy) just prior to impact and therefore easier to handle; andsince the moment of inertia around the center of gravity is increased atthe instant of impact, the player's swing or stroke is not overcome bythe ball, and hitting the ball is more comfortable.

[0065] As to this improvement in hitting comfort, it has been found thatthe non-impact position at the time of center impact (the node ofvibration on the grip in two-node flexural vibration) is approximately 7cm from the grip end (the grip fulcrum; the center of a standard gripposition).

[0066] As to ease of use, since snap movement around the wrist iseasier, head speed is higher in the swing or stroke action of hittingthe ball, which means that the ball is hit faster and it is easier toput spin on the ball, allowing the player to swing more easily.Therefore, the present invention ameliorates the drawback of moredifficult swinging when applied to the longer rackets have beenincreasingly popular in recent years.

[0067] Also, since the loading member is isolated by the soft materialregion interposed in the grip end member that includes the end cap, theimpact vibration produced during hitting is effectively suppressed orabsorbed (attenuated), making hitting more comfortable. Furthermore,since the weight is balanced between the inside and outside of the gripend bottom, it will not fall out during play.

[0068] Overall, discomfort such as numbness or excessive load on thebody caused by impact is reduced, which makes the implement easier touse and prevents injury, and thereby helps to raise the level of play.

1. A grip end bottom weight provided protruding from a grip end bottomof a ball-hitting implement, wherein said grip end bottom weight ischaracterized in that a soft material, capable of absorbing impactvibrations and in composite integration with a loading member composedof a high specific gravity substance, is formed so as to have axiallysymmetric wall thickness in cross section and to be mounted byelastically deforming a body component thereof in a mounting hole formedin a grip end bottom, with at least half of said body component of saidsoft material protruding from said grip end bottom when mounted.
 2. Thegrip end bottom weight according to claim 1, wherein: said compositeintegration is obtained in said loading member by being incorporatedinto, embedded in, surrounded by, joined to, compounded with, ordispersedly compounded with, in a matrix of said soft material; saidmounting hole is formed by boring out a bottom surface of a grip endmember that includes an end cap or an end rubber; and said soft materialis mounted by being removably fitted, pressed, squeezed, or threadedinto said mounting hole by stored elastic energy.
 3. The grip end bottomweight according to claim 1 or 2, wherein said soft material isnon-rotatably restrained in said mounting hole and is balance-mounted,with one half of said body component housed inside a grip via side wallsof said mounting hole, and with another half of said body componentprotruding from said grip end bottom.
 4. The grip end bottom weightaccording to any one of claims 1 to 3, wherein said soft material ismolded in an approximate shape of a barrel, and a circumferential grooveor flange is provided around a large-diameter middle thereof and fittedto a peripheral edge of said mounting hole, allowing said weight to beremovably mounted.
 5. The grip end bottom weight according to any one ofclaims 1 to 4, wherein said loading member is disposed inside of twoends of said soft material, with its weight divided into an internalweighting element and an external weighting element when mounted.
 6. Thegrip end bottom weight according to any one of claims 1 to 5, whereinsaid grip end bottom weight weighs between 10 and 120 g, thus shiftingcenter of impact (a node of vibration) on a grip to a portion to begrasped by hand (a grip fulcrum).
 7. A grip end bottom weightingstructure, characterized in that: the grip end bottom weight accordingto any one of claims 1 to 6 is removably mounted on a grip end of aball-hitting implement; moment of inertia around center of gravity isincreased at a time a ball is hit; and an impact vibration issuppressed, absorbed or attenuated.
 8. A grip end bottom weightingstructure provided protruding from a grip end bottom of a ball-hittingimplement, wherein said grip end bottom weighting structure ischaracterized by being comprised of: a grip end member that includes anend cap or an end rubber and is provided with a mounting hole formed ina planar center thereof, a loading member composed of a high specificgravity substance, and a soft material which is in composite integrationwith said loading member; and wherein said soft material has axiallysymmetric wall thickness in cross section and is formed so as to bemounted by elastic deformation of a body component thereof, at leasthalf of said body component of said soft material is fixed to protrudefrom said grip end bottom of said ball-hitting implement, and a softmaterial region of said soft material is disposed so as to isolate saidloading by means of said grip end member, thus allowing moment ofinertia around center of gravity to increase at a time a ball is hit andan impact vibration to be suppressed, absorbed, or attenuated.
 9. Thegrip end bottom weighting structure according to claim 8, wherein saidcomposite integration is obtained in said loading member by beingincorporated into, embedded in, surrounded by, joined to, compoundedwith, or dispersed in a matrix of said soft material, said mounting holeis formed by boring out a bottom surface of a grip end member thatincludes said end cap or said end rubber, and said soft material ismounted by being removably fitted, pressed, squeezed, or threaded intosaid mounting hole by stored elastic energy; and wherein said softmaterial is non-rotatably restrained in said mounting hole and isbalance-mounted, with one half of said body component housed inside agrip via side walls of said mounting hole, and with another half of saidbody component protruding from said grip end bottom.
 10. The grip endbottom weighting structure according to claim 8 or 9, wherein said softmaterial is molded in an approximate shape of a barrel, and acircumferential groove or flange is provided around a large-diametermiddle thereof and fitted to a peripheral edge of said mounting hole,allowing said weight to be removably mounted.
 11. The grip end bottomweighting structure according to any one of claims 8 to 10, wherein saidloading member is disposed inside of two ends of said soft material,with its weight divided into an internal weighting element and anexternal weighting element when mounted on said ball hitting implement.12. The grip end bottom weighting structure according to any one ofclaims 8 to 11, wherein said ball-hitting implement is provided with twoend caps or end rubbers or is formed thick so that said mounting hole isprovided in two levels or steps, thus allowing a mounting position to bechanged.
 13. The grip end bottom weighting structure according to anyone of claims 8 to 12, wherein an application of weight of between 10and 120 g is made to said grip end bottom of said ball-hittingimplement, thus shifting center of impact (a node of vibration) on agrip to a portion to be grasped by hand (the grip fulcrum).
 14. The gripend bottom weighting structure according to any one of claims 7 to 13,wherein said ball-hitting implement is one selected from among a tennisracket, a soft tennis racket, a squash racket, a badminton racket andanother racket, a baseball or softball bat, a golf club, and a hockeystick.